Betaines

Betaines are a family of organic compounds that exist as zwitterions, containing a positively charged quaternary ammonium group and a negatively charged carboxylate within the same molecule. The term commonly refers to N,N,N-trimethylglycine, the simplest and best-known member, also called glycine betaine.

Natural occurrence and role: Glycine betaine occurs widely in plants, including sugar beets, spinach, and cereals, and accumulates in response to osmotic stress. As osmoprotectants, betaines help stabilize proteins and membranes and support cell function under high salinity or drought. They are also found in various bacteria and marine organisms as compatible solutes.

Biosynthesis and metabolism: In animals and humans, betaine is produced from choline and serves as a methyl donor in the methionine cycle via the enzyme betaine-homocysteine methyltransferase, converting homocysteine to methionine. This contributes to cellular methylation potential.

Applications: In cosmetics and detergents, several alkyl betaines are used as mild, amphoteric surfactants, for example cocamidopropyl betaine. In nutrition, glycine betaine is consumed as a dietary supplement and is studied for effects on homocysteine levels and methylation status.

Safety and regulation: Betaines are generally regarded as safe for many uses, but individual responses vary, and effective dosage depends on the application. Labeling and regulatory status vary by country and product type.